James Cameron - Challenger Deep Submarine record dive Mariana Trench

Credit - National Geographic2013 by James Cameron

Cameron outlines some of the ways one can perish in the Challenger Deep submersible, in his own words, below.IMPLOSIONThe obvious one. You’ve miscalculated the design of your sphere. As you approach the bottom, with barely a warning groan, the sphere buckles suddenly. Faster than you can scream, you’re smashed into jam.PENETRATOR FAILUREThere’s a dead short someplace and one of the pins in your electrical penetrator—the device that feeds power and control signals through the sphere wall—melts, causing the penetrator to fail. The water jet erodes the interior of the penetrator, allowing seawater to blast inside, at 16,000 psi.FREEZINGIf you get stuck on the bottom your weights don’t drop, and it’s a race between your life support running out and freezing to death. But you’ve got 60 hours of scrubber and O2, so freezing wins. Because the water outside is just above 0°C … icewater.FIREElectrical fires can break out among all of the sub’s gadgets, and with O2 pumping into the pilot sphere, fires can grow quickly. Although a fire extinguisher is stored in the sphere, it may not be enough to extinguish a sizable fire.VIEWPORT FAILUREYou’re looking out the viewport when suddenly you see cracks developing. The cracks quickly web throughout the thick volume of the acrylic, and it starts to give way. Then BANG! The cork pops and the sea hammers in like a supersonic piston.ADRIFTOnly one ascent weight drops instead of both. So you ascend close to the surface but not all the way. Over the next ten hours a two-knot midwater current takes you 20 miles away, and the surface crew has no idea where you are, because you’re not at the surface.Three Unexpected Dangers of Deep-Ocean ExplorationThe “behind the scenes” information posted on the DEEPSEA CHALLENGE website provides incredible insight into the types of challenges—and logistics—that go into planning and executing an expedition of this size and scope. There are surprises everywhere—things one might never have thought to consider on their own and the planning for which there are few, if any, precedents. The work of the DEEPSEA CHALLENGE is an exercise for mystery- and puzzle-loving minds. Three expedition risks that theDEEPSEA CHALLENGE team has anticipated and addressed that might take nondivers by surprise are listed below.HYDROTHERMAL VENT-INDUCED MELTDOWNAs first reported in expedition blogger Dr. Joe MacInnis’s March 18 entry, several of the expedition’s members, including the legendary Captain Don Walsh, one of two people ever to have been to the Challenger Deep prior to this expedition, discussed the risks of “flying a research sub too close to a hydrothermal vent,” where they “casually mention[ed]” that the water temperature approached 700 degrees and would melt a sub’s viewport.SEAFLOOR COMMUNICATIONS CABLE ENTANGLEMENTSubmarine communications cables are cables that traverse the seafloor between land-based stations to extend telecommunication signals across stretches of ocean. Were the sub to become entangled in these cables, it might prevent it from returning to the surface.HYPOTHERMIA AND HYPERTHERMIAThe DEEPSEA CHALLENGER submersible is a state-of-the-art vehicle—but it is not equipped with a thermostat that can adjust internal temperatures for comfort. The temperature range for a dive borders on the extreme. As the National Geographic expedition website reports, “the temperature will drop from sauna-like at the surface to meat-locker cold at the bottom.” Cameron will dive wearing many layers but the risk of overheating or freezing is significant. In a personal communication to his team, Cameron described a recent experience with heatstroke-like symptoms as he waited inside the sub’s unventilated pilot sphere to be launched into the ocean:“Hyperthermia early in the dive (and throughout shallow test dives) is a hazard in this vehicle, at least as much as hypothermia late in a deep dive. I found my mental performance slipping after two hours at 102 degrees/100% humidity [while piloting the sub for a test dive]. It doesn’t sound that hot but with zero evaporative cooling available in such a tiny airspace, I’m sure my core temp was going up to match air temp. I got sub internal temp back down to 97 degrees. But by then I was trashed, and had lost several pounds in water.”